The semiconductor integrated circuit (IC) industry has experienced exponential growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component (or line) that can be created using a fabrication process) has decreased. This scaling down process generally provides benefits by increasing production efficiency and lowering associated costs. Such scaling down has also increased the complexity of processing and manufacturing ICs.
For example, multi-gate devices have been introduced in an effort to improve gate control by increasing gate-channel coupling, reduce OFF-state current, and reduce short-channel effects (SCEs). One such multi-gate device that has been introduced is the fin field-effect transistor (FinFET). The FinFET gets its name from the fin-like structure which extends from a substrate on which it is formed, and which is used to form the FET channel. FinFETs are compatible with conventional complementary metal-oxide-semiconductor (CMOS) processes and their three-dimensional structure allows them to be aggressively scaled while maintaining gate control and mitigating SCEs. N-type FinFETs and p-type FinFETs may have different material compositions in respective fins (e.g., Si in fins of n-type FinFET and SiGe in fins of p-type FinFET), which enhances carrier mobility of both types of FinFETs and improves device performance. However, fin width control during the fin patterning can be challenging. For example, fins with different material compositions suffer from different lateral losses during fabrication, resulting in inconsistent fin widths between n-type FinFETs and p-type FinFETs. Therefore, although conventional fin patterning methods have been generally adequate for their intended purposes, they are not satisfactory in all respects.